An agger (Latin) is an ancient Roman embankment or any artificial elevation. The most common agger was the ridge or embankment on which Roman roads were built to give the proper draining base. The agger was constructed by excavating the line of the road, building a firm foundation, refilling and compressing the soil, adding more soil from digging drainage ditches or fosses on one or both sides of the road, then surfacing with graded layers of stone and cobbles. The material used to build the aggers was dug from lateral ditches.